#include <bits/stdc++.h>
//#define int long long

using namespace std;
using LL = long long;
using P = pair<int, int>;

#define FOR(i, a, n) for(int i = (int)(a); i < (int)(n); ++i)
#define REP(i, n) FOR(i, 0, n)

#define pb(a) push_back(a)
#define all(x) (x).begin(),(x).end()

template<typename T>
vector<T> make_v(size_t a){return vector<T>(a);}
template<typename T,typename... Ts>
auto make_v(size_t a, Ts... ts) {return vector<decltype(make_v<T>(ts...))>(a, make_v<T>(ts...)); }

template<typename T,typename V>
typename enable_if<is_class<T>::value == 0>::type
fill_v(T &t, const V &v){ t = v; }

template<typename T,typename V>
typename enable_if<is_class<T>::value != 0>::type
fill_v(T &t, const V &v){ for(auto &e : t) fill_v(e, v); }

const int INF = (int)1e9;
const LL INFL = (LL)1e18;
const int MOD = 1e9 + 7;

signed main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    
    int q;
    cin >> q;
    REP(i, q)
    {
        LL a, b, c;
        cin >> a >> b >> c;
        if(c == 1)
        {
            cout << -1 << endl;
            continue;
        }

        vector<LL> vec;
        while(a > 0)
        {
            vec.push_back(a % c);
            a /= c;
        }
        reverse(all(vec));

        int cnt = vec.size() - 1;
        REP(i, vec.size())
        {
            if(vec[i] > 0) cnt++;
        }

        if(vec.size() >= 2 && vec[1] > 0 && vec[0] * c + vec[1] <= (c-1)*2) cnt--;
        cout << b * cnt << endl;
    }
}